In a modern communication system, a relay technology is applied more and more widely. An LTE-A (LTE-Advance, LTE-Advanced) technology is taken as an example. The LTE-A technology is an evolved version of an LTE (Long Term Evolution, long term evolution) technology, and in the LTE-A technology, a radio link between an eNB and a terminal is split into a link between the eNB and a relay node and a link between the relay node and the terminal by adopting a relay technology, so as to implement better capacity and coverage. FIG. 1 is a schematic diagram of an LTE-A radio access network in the prior art. The network includes a donor eNodeB (DeNB, Donor eNodeB), a relay node (RN, Relay Node), and three user equipments (UE, User Equipment) that are subordinate to the relay node. A user equipment is also a terminal. Three terminals are marked as a UE1, a UE2, and a UE3. Interfaces between the three terminals and the RN are Uu interfaces; an interface between the RN and the DeNB is a Un interface; an interface between eNBs is called an X2 interface, and an interface between the eNB and a mobility management entity (MME, Mobility Management Entity) or a gateway (GW, Gateway) is an S1 interface. A message transmitted through an X2 interface is called an X2 message, and a message transmitted through an S1 interface is called an S1 message.
In a relay architecture provided in the prior art, if an S1 message is used at a Un interface, the eNB uses the S1 message on an EPC (Evolved packet core network, evolved packet core network) side; and if an X2 message is used at the Un interface, the eNB uses the X2 message on the EPC side. The foregoing process is described in the following by taking that a relay station initiates a handover request message to an eNB by using an S1 message in a handover process of a user equipment as an example.
After receiving a handover request message (S1-AP: HO required message), the eNB may modify only an S1AP UE ID (an S1 application protocol identifier of a user equipment) of the S1 message, and keeps the remaining part unchanged, and then forwards the S1 handover request message (S1AP: HO required message) to the MME to perform a corresponding S1 handover procedure. The S1-AP or S1AP here represents an S1 Application Protocol (S1 application protocol). The prior art has at least the following problem: It is unable to properly determine whether an X2 interface or an S1 interface is used for handover, which may cause a handover failure.